This invention relates to means for protecting soft oral tissue from the irritating effects of dental devices and/or the provision of medicaments or therapeutics in measured doses within the oral cavity.
Devices for timed release of therapeutic drugs have been described in the prior art. For example, the National Institute for Dental Research has described a preformed kidney shaped polymer sac containing fluoride salt in a matrix of hydrophilic polymer that moderates and controls the diffusion of fluoride ion into the oral environment. These devices have been attached to a tooth by an adhesive. Their periodical replacement is time costly and their size makes them cumbersome. Despite these difficulties their use is contemplated to control rampant caries, for example.
Orthodontics is a discipline within dentistry that is concerned with the movement of teeth to achieve satisfactory occlusive interlation between teeth. In order to achieve this, metal or ceramic devices called brackets are attached to the teeth. The brackets can be adhered to each other by mechanical interlocks formed in the bracket and to the tooth by micromechanical interlocks formed by acid etching of the dental enamel prisms of hydroxy apatite. A layer of a self curing or actinic light cured resin or cement is applied between these interfaces and hardened to retain the bracket even when subjected to considerable force. Force is applied through bracket wire that travels between brackets attached to the several teeth and is placed under tension by mechanical forces induced by beding the wire. The relief of the induced tension occurs as the teeth move. The forces cause the breakdown of tissue on one side and the build-up of tissue on the other. Because there is excessive force required at the wire terminus or in molar teeth that have multiple roots, it is common that the bracket have a continuous band surrounding it in these situations. The bracket extends buccally and has a receptacle for the wire, and is sufficiently large to permit the transfer of the wire stress to the tooth. The protrusion of the bracket toward the cheek and lips (or tongue in specialized applications), and the sharp and distinct edges of the bracket, and the presence of wire ends are all irritating factors for the adjacent soft tissue and the patient. In due course the tissue may become calloused. Corrective methodology for this problem is for the patient to apply beeswax to the bracket where and when required, especially during the break-in period.
The presence of this bulky bracket makes cleaning of the teeth difficult. The tooth is no longer self-cleansing and it is difficult for the patient to clean the tooth mechanically. Plaque frequently builds-up around the apical walls of the bracket, causing conditions conducive to caries and at the gingival crest gingivitis, and possibly inducing more serious periodontal conditions. These and other abnormal conditions suggest the need to provide therapeutical substrates locally on a sustained basis.
In one preferred form the device consists of a light curing elastomeric material that may, depending on the application, contain a therapeutic agent that is released into the oral cavity through extraction by saliva.